Vastly improved survival of premature infants has prompted investigation into the special problems and needs of this at-risk population. Most past evaluations have focused on neuromotor, sensory and cognitive impairments. Behavioral problems more recently emerged as a poorly understood morbidity of premature infants. This project will examine the development of behavioral and social problems in children who were born prematurely, under the hypothesis that the problems result from a combination of biologic and environmental factors and that their emergency may e recognized in infancy. The specific aims are as follows: 1) To examine longitudinally the onset and persistence of behavioral problems in premature children. Data from three multisite or nationally representative cohorts followed longitudinally will be examined to determine components of infant temperament or toddler behavior that predicts subsequent behavior problems. Comparisons will be made between tendencies in normal and low or very low birthweight groups. 2) To delineate risk factors present in the neonatal period leading to behavioral problems. Factors such as birthweight, gestational age, evidence of central nervous system injury (e.g., intraventricular hemorrhage), and bronchopulmonary dysplasia will be analyzed. 3) To develop methods for risk adjustment for behavior problems based on factors not identified in the neonatal period. Evaluations of the three cohorts will determine the effects of factors hypothesized to mediate the depression, family structure, chronic illness, and structured developmental intervention. Dr Stolz recently finished his fellowship training in neonatology and has completed an M.P.H. program at the Harvard School of Public Health. During the proposed project period, he will undertake additional coursework in biostatistical methods and child behavior. The project is sponsored by Marie C. McCormick, MD ScD, who is Professor and Chair of Maternal and Child Health at the Harvard School of Public Health and Professor of Pediatrics at Harvard Medical School. She brings to the project extensive experience in the rigorous evaluation of long-term outcomes of premature infants, as well as a history of successful mentoring experiences. She will ensure that the project remains firmly grounded in sound methodology and sharply focused toward questions with clinical relevance. A panel of consultants will further advise Dr. Stolz through the course of the project.